Dear
Welcome to HCM
We understand your concerns
I went through your details. You mentioned a visit to a doctor and heart related check ups. That doctor could not find any problem with your heart. At the same time, the doctor must have used his knowledge and investigations to have more diagnostics. In fact, the doctor found nothing wrong with you and therefore, told you so.
Breathing trouble can also be caused by obsession and anxeity. You feel that you have breathing problem and obsess (focus) onto the problem itself. Naturally uneasiness builds up. If you do not have any diversion tactics, the piled up uneasiness leads to
anxiety and
restlessness. Anxiety and restlessness causes
hyperventilation and hyperventilation in turn can cause breathlessness feeling and / or
chest pain. Don't worry. I suggest you to
consult a psychologist for further therapy options.
If you still need my assistance in this regard, please use this link. http://goo.gl/aYW2pR. Please remember to describe the whole problem with full detail.
Hope this answers your query. Please feel free to post follow up queries. Available for further clarifications.
Good luck. Take care.